Investment Securities - Narrative (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($) Investment	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) Investment	Dec. 31, 2020 USD ($)
Debt Securities, Available-for-sale [Line Items]
Carrying value of securities pledged to secure public deposits and other contractual obligations	$ 413,800		$ 281,700
Pledging requirements for credit derivatives and SWAP agreements - securities		$ 0	$ 23,000
Number of investments in non federal issuer representing more than 10% of shareholder's equity | Investment	0		0
Maximum investment in any single non-federal issuer representing shareholders equity	10.00%		10.00%
Fair value HTM in unrealized loss with no ACL	$ 136,456		$ 89,837
Unrealized loss included in fair value of securities HTM in unrealized loss position for which an ACL has not been recorded	22,714		984
Fair value AFS in unrealized loss with no ACL	264,770		179,992
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	46,823		2,300
Fair value of securities AFS in unrealized loss position for which an ACL has been recorded, net of allowance	82,200
Unrealized loss position included in fair value of securities AFS in unrealized loss position for which an ACL has been recorded	9,500
Allowance for credit losses	1,299		929
Debt securities	347,479		317,007
Investment securities available-for-sale (amortized cost $403,774 and $319,474, net of allowance for credit losses of $1,299 and $929 at September 30, 2022 and December 31, 2021, respectively)	403,774		319,474
Securities, Held-to-Maturity, Amortized Cost	159,170		176,983
Securities Held-to-Maturity, Gross Unrealized Gains	0		2,403
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss	(22,714)		(984)
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	136,456		178,402
Corporate Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Fair value AFS in unrealized loss with no ACL	500		779
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	1		1
Allowance for credit losses	$ 1,299	815	929	$ 869
Number of securities | Investment	39
Debt securities	$ 82,204		90,291
Investment securities available-for-sale (amortized cost $403,774 and $319,474, net of allowance for credit losses of $1,299 and $929 at September 30, 2022 and December 31, 2021, respectively)	91,683		91,231
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	1,000
Allowance for credit losses	1,300
Held-to-maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable	339
Residential Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair value HTM in unrealized loss with no ACL	136,456		89,837
Unrealized loss included in fair value of securities HTM in unrealized loss position for which an ACL has not been recorded	22,714		984
Fair value AFS in unrealized loss with no ACL	259,561		176,423
Unrealized loss included in fair value of securities AFS in unrealized loss position for which an ACL has not been recorded	46,514		2,276
Allowance for credit losses	0		0
Debt securities	260,566		221,105
Investment securities available-for-sale (amortized cost $403,774 and $319,474, net of allowance for credit losses of $1,299 and $929 at September 30, 2022 and December 31, 2021, respectively)	307,074		222,623
Securities, Held-to-Maturity, Amortized Cost	159,170		169,984
Securities Held-to-Maturity, Gross Unrealized Gains	0		2,369
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss	(22,714)		(984)
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	136,456		171,369
U.S. Government Corporations and Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Securities, Held-to-Maturity, Amortized Cost			6,999
Securities Held-to-Maturity, Gross Unrealized Gains			34
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss			0
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest			$ 0
Other Noninterest Income [Member] | Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Net realized gain on investment securities	$ (207)	$ 164